Age-specific features of estrous cycles and folliculogenesis in GC female rats selected by catatonic reactivity.

A decrease in the total count of follicles in the diestrus and proestrus and higher incidence of permanent estruses were found in 3-month-old females of the catatonic GC rat strain in comparison with Wistar females (control). At the age of 6-12 months, GC females had lower incidence of long estrus and diestrus. The estrous cycle of GC females was shorter than of Wistar rats. With aging (at the age of 18 months), the counts of growing and maturing follicles significantly decreased. Higher counts of growing single-layer and bilayer follicles were found in 18-month-old GC females. Differences in the length of estrus and diestrus and in the incidence of abnormal phases in the two strains also disappeared at this age. Selection by high catatonic reactivity was associated with a decrease in body weight.